Yes. Start measuring where you start shaping and go STRAIGHT up. I usually put a lifeline in on the first decrease row to make it easier to measure and make sure the fronts and backs match up. Makes counting easier, too.

ETA: There are no stupid questions. Only stupid people who don't ASK questions! You're NOT one of those!

Yes-- you begin measuring from the first decrease row. A great way to do this is to lay the piece out flat on the floor or a table. Let's say it's the back of the bolero. Take a wooden metre or yard stick and lay it across, horizontally, where the first decrease rows are on the arm holes. Then take a ruler or tape measure and measure up vertically from that. You'll get the most accurate measurement.